In a conventional television (TV) system, a TV signal comprises a luminance component and a chrominance component. Upon receiving the TV signal, the TV system separates the luminance component and the chrominance component (i.e., a Y/C separation) via a filter. However, when a part of an image frame 110 in FIG. 1 comprises high frequency luminance in the spatial domain (i.e., the luminance varies very frequently in spatial domain), luminance and chrominance data of a partial TV signal cannot be accurately restored, e.g., the high frequency luminance components may be treated as chrominance components to result in rainbow-like chrominance on the image frame. The rainbow-like chrominance is also referred to as a cross-color phenomenon that causes defects on the image frame.
When cross-color occurs, for a pixel at a position on consecutive static frames, chrominance values of the pixel at the same position of two associated frames (e.g., two frames of a two-frame interval in a National Television System Committee (NTSC) system, or two frames of a four-frame interval in a Phase Alternation Line (PAL) system) are respectively C+ΔC. and C−ΔC., where C is an ideal chrominance value of the pixel at the position, ΔC. is a chrominance deviation caused by the high frequency luminance. Therefore, in order to overcome the issue of cross-color, an average chrominance value of the pixel at the same position of the two associated frames is calculated, and the calculated average chrominance value is regarded as the chrominance value of the pixel at the same position of the two associated frames. However, the foregoing method for overcoming the issue of cross-color is only suitable for consecutive static frame. More specifically, when a moving object contains high frequency luminance in spatial domain of an image frame, not only does the foregoing method not overcome the issue of cross-color, but a greater error in chrominance of the image frame may also result.